We studied the expression of two vertebrate homeobox genes, Otx1 and Otx2, related to orthodenticle, a gene expressed in the developing head of Drosophila. Both genes are expressed in restricted regions of the developing rostral brain including the presumptive cerebral cortex and olfactory bulbs. The expression patterns of the two genes in diencephalon suggest that they both have a role in establishing the boundary between presumptive dorsal and ventral thalamus. They are also expressed in regions of the developing olfactory, auricolar and ocular system, including the covering of the optic nerve. Otx1 expression is detectable from day 8 of gestation in telencephalic, diencephalic and mesencephalic regions. From day 10.5 of gestation its expression extends to some metencephalic areas. Otx2 appears to be already expressed in the epiblast of prestreak embryos. It persists in the entire embryonic ectoderm for some time after the onset of gastrulation. In midstreak embryos its expression appears progressively restricted to the anterior embryonic ectoderm corresponding to presumptive fore‐ and mid‐brain. In early midgestation embryos it is expressed in telencephalic, diencephalic and mesencephalic regions but from day 11.75 of gestation its expression disappears from dorsal telencephalon and is confined to diencephalic and mesencephalic regions. Otx2 is one of the earliest genes expressed in the epiblast and immediately afterwards is expressed in anterior neuroectoderm, demarcating rostral brain regions even before headfold formation. Its gene product contains a homeodomain of the bicoid class and is able to recognize and transactivate a bicoid target sequence.

In December 2019, an initial cluster of interstitial bilateral pneumonia emerged in Wuhan, China. A human-to-human transmission was assumed and a previously unrecognized entity, termed coronavirus disease-19 (COVID-19) due to a novel coronavirus (SARS-CoV-2) was described. The infection has rapidly spread out all over the world and Italy has been the first European country experiencing the endemic wave with unexpected clinical severity in comparison with Asian countries. It has been shown that SARS-CoV-2 utilizes angiotensin converting enzyme 2 (ACE2) as host receptor and host proteases for cell surface binding and internalization. Thus, a predisposing genetic background can give reason for interindividual disease susceptibility and/or severity. Taking advantage of the Network of Italian Genomes (NIG), here we mined whole-exome sequencing data of 6930 Italian control individuals from five different centers looking for ACE2 variants. A number of variants with a potential impact on protein stability were identified. Among these, three more common missense changes, p.(Asn720Asp), p.(Lys26Arg), and p.(Gly211Arg) were predicted to interfere with protein structure and stabilization. Rare variants likely interfering with the internalization process, namely p.(Leu351Val) and p.(Pro389His), predicted to interfere with SARS-CoV-2 spike protein binding, were also observed. Comparison of ACE2 WES data between a cohort of 131 patients and 258 controls allowed identifying a statistically significant (P value < 0.029) higher allelic variability in controls compared with patients. These findings suggest that a predisposing genetic background may contribute to the observed interindividual clinical variability associated with COVID-19, allowing an evidence-based risk assessment leading to personalized preventive measures and therapeutic options.

Udd b , c , d , on behalf of the LGMD workshop study group

The BIO14.6 hamster is a widely used model for autosomal recessive cardiomyopathy. These animals die prematurely from progressive myocardial necrosis and heart failure. The primary genetic defect leading to the cardiomyopathy is still unknown. Recently, a genetic linkage map localized the cardiomyopathy locus on hamster chromosome 9qa2.1-b1, excluding several candidate genes. We now demonstrate that the cardiomyopathy results from a mutation in the delta-sarcoglycan gene that maps to the disease locus. This mutation was completely coincident with the disease in backcross and F2 pedigrees. This constitutes the first animal model identified for human sarcoglycan disorders.

No abstract

BackgroundMyosin heavy chain 7 (MYH7)-related myopathies are emerging as an important group of muscle diseases of childhood and adulthood, with variable clinical and histopathological expression depending on the type and location of the mutation. Mutations in the head and neck domains are a well-established cause of hypertrophic cardiomyopathy whereas mutation in the distal regions have been associated with a range of skeletal myopathies with or without cardiac involvement, including Laing distal myopathy and Myosin storage myopathy. Recently the spectrum of clinical phenotypes associated with mutations in MYH7 has increased, blurring this scheme and adding further phenotypes to the list. A broader disease spectrum could lead to misdiagnosis of different congenital myopathies, neurogenic atrophy and other neuromuscular conditions.ResultsAs a result of a multicenter Italian study we collected clinical, histopathological and imaging data from a population of 21 cases from 15 families, carrying reported or novel mutations in MYH7. Patients displayed a variable phenotype including atypical pictures, as dropped head and bent spine, which cannot be classified in previously described groups. Half of the patients showed congenital or early infantile weakness with predominant distal weakness. Conversely, patients with later onset present prevalent proximal weakness. Seven patients were also affected by cardiomyopathy mostly in the form of non-compacted left ventricle. Muscle biopsy was consistent with minicores myopathy in numerous cases. Muscle MRI was meaningful in delineating a shared pattern of selective involvement of tibialis anterior muscles, with relative sparing of quadriceps.ConclusionThis work adds to the genotype-phenotype correlation of MYH7-relatedmyopathies confirming the complexity of the disorder.Electronic supplementary materialThe online version of this article (doi:10.1186/s13023-016-0476-1) contains supplementary material, which is available to authorized users.

To enhance our understanding of the autosomal recessive limb-girdle muscular dystrophy (LGMD), patients from six genetically distinct forms (LGMD2A to LGMD2F) were studied with antibodies directed against four sarcoglycan subunits (alpha-, beta-, gamma-, delta-SG), dystrophin, beta-dystroglycan (beta-DG) and merosin. All patients with LGMD2A and 2B had a mild clinical course while those with a primary sarcoglycan mutation (LGMD2C to 2F) had a range of clinical severity. Dystrophin and merosin immunofluorescence pattern was positive in patients with all six AR LGMDs. The majority of patients with a severe Duchenne-like phenotype presented total absence of the SG complex. However, some exceptions were found in 13q linked patients, indicating that the presence of a certain labelling for components of the SG may not be prognostic for a milder phenotype. The observation that the primary absence of alpha-SG results in the total absence of beta- and delta-SG but not of gamma-SG suggests that the alpha-, beta- and delta-subunits of sarcoglycan may be more closely associated. A secondary reduction in dystrophin amount was seen in patients with primary sarcoglycan mutations, which was most marked in patients with primary beta-, gamma- and delta-SG deficiencies. In contrast, beta-DG staining was retained in all patients, suggesting that the association between SG and DG subcomplexes is not so strong. Based on the above findings, we have refined the model for the interaction among the known glycoproteins of the sarcoglycan complex, within the DGC.

Congenital myopathies are a group of genetic muscle disorders characterized clinically by hypotonia and weakness, usually from birth, and a static or slowly progressive clinical course. Historically, congenital myopathies have been classified on the basis of major morphological features seen on muscle biopsy. However, different genes have now been identified as associated with the various phenotypic and histological expressions of these disorders, and in recent years, because of their unexpectedly wide genetic and clinical heterogeneity, next-generation sequencing has increasingly been used for their diagnosis. We reviewed clinical and genetic forms of congenital myopathy and defined possible strategies to improve cost-effectiveness in histological and imaging diagnosis.